Thermo-osmosis of mixtures of water and methanol through a Nafion membrane

Mass transport of mixtures of water and methanol through a Nafion membrane as a function of the temperature difference between the two sides of the membrane was measured under different experimental conditions. The results show that the composition of the solutions, the temperature difference across the membrane, and the mean temperature in the membrane cell are governing factors in the thermo-osmotic transport process. In all cases studied, the thermo-osmotic flux through the membrane goes from the low temperature side to the high temperature side, and it increases linearly with the temperature difference. Moreover, the flux also increases with the mean temperature in the membrane cell. The thermo-osmotic coefficient of methanol in the membrane is higher than that of water. For water/methanol mixtures, the total flux through Nafion membrane can be larger than the fluxes of pure solvents, and it increases with the methanol content for water/methanol mixtures.